list.yml

rules:
  - id: list-length-compare-0
    pattern-either:
      - pattern: List.length $L = 0
      - pattern: List.length $L <> 0
      - pattern: List.length $L > 0
      - pattern: List.length $L >= 1
      # doesn't find in ValueDomain: List.length ci.cfields > 0
      # doesn't find in MyLiveness: List.length s.labels = 0
    message: computing list length is inefficient for emptiness checking, compare with [] instead
    languages: [ocaml]
    severity: WARNING

  - id: list-length-compare-n
    patterns:
      - pattern-either:
        - pattern: List.length $L = $N
        - pattern: List.length $L <> $N
        - pattern: List.length $L > $N
        - pattern: List.length $L >= $N
        - pattern: List.length $L < $N
        - pattern: List.length $L <= $N
      - metavariable-pattern:
          metavariable: $N
          patterns:
            - pattern-not: "0" # covered by list-length-compare-0
            - pattern-not: List.length ... # covered by list-length-compare-list-length
    message: computing list length is inefficient for length comparison, use compare_length_with instead
    languages: [ocaml]
    severity: WARNING

  - id: list-length-compare-list-length
    pattern-either:
      - pattern: List.length $L1 = List.length $L2
      - pattern: List.length $L1 <> List.length $L2
      - pattern: List.length $L1 > List.length $L2
      - pattern: List.length $L1 >= List.length $L2
      - pattern: List.length $L1 < List.length $L2
      - pattern: List.length $L1 <= List.length $L2
    message: computing list length is inefficient for length comparison, use compare_lengths instead
    languages: [ocaml]
    severity: WARNING

  - id: list-function-temporary-combine
    patterns:
      - pattern: $LF ... (List.combine ... ...)
      - metavariable-pattern:
          metavariable: $LF
          pattern-either:
            - pattern: List.iter
            - pattern: List.iteri
            - pattern: List.map
            - pattern: List.mapi
            - pattern: List.rev_map
            - pattern: List.fold_left
            - pattern: List.fold_right
            - pattern: List.for_all
            - pattern: List.exists
    message: unnecessary temporary combined list, use 2-suffixed operation directly
    languages: [ocaml]
    severity: WARNING

  - id: list-map-flatten
    patterns:
      - pattern-either:
        - pattern: $LF (List.map ... ...)
        - pattern: $LF @@ List.map ... ...
        - pattern: List.map ... ... |> $LF
        - pattern: (... |> List.map ... ...) |> $LF
      - metavariable-pattern:
          metavariable: $LF
          pattern-either:
            - pattern: List.flatten
            - pattern: List.concat
    message: use List.concat_map instead
    languages: [ocaml]
    severity: WARNING